This application claims the benefit of a priority under 35 USC 119 to French Patent Application No. 01 07521 filed Jun. 6, 2001, the entire contents of which are hereby incorporated by reference.
This invention relates to a radiographic apparatus to be used, for example, for mammography, and to a support for an object to be imaged by such an apparatus.
A mammography apparatus or mammographs are used for examining the breasts of a patient using X-rays. The image is acquired using an image receiver which may be in the form of a photographic plate or of a digital sensing means, GE Medical Systems Global Technology Company, LLC, has commercially available an analog or digital mammographs under the names Senographe 700T, Senographe 800T and Senographe 2000D. These mammographs apparatus have a vertical column on which an examination arm is mounted which can move up and down vertically. The examination arm has a source at its upper end that comprises the means for delivery of radiation, such as X-rays. The arm has means for receiving an image at its other end. A means for compression, such as a paddle, is slidably mounted on the arm, sliding in the direction of propagation of the radiation. This compression paddle allows the operator performing the examination to compress or maintain the breast being examined. The means for receiving an image comprises equipment allowing the radiation delivery to be controlled, notably a radiation measurement cell. In the case of a digital apparatus, the means for receiving comprises an image reception screen.
The means for image receiving has slideways on its top face for mounting means for stray radiation elimination. This means comprises a grid network formed of lead plates, parallel to the radiation, which can move with a translatory movement perpendicular to the direction of the radiation propagation. FIG. 1 is a partial diagrammatic view of the apparatus showing the means 2 for receiving, part of the examination arm 4, and this means 6.
More precisely, the means 6, which is commonly known by the names Bucky or Potter, has, at its lower part, means for sliding which cooperates with the slideways provided on the upper part of the means for image receiving to allow the means 6 to be mounted on the means for image receiving by sliding it in the direction of arrow 8. On its back part directed towards the examination arm 4, means 6 has electrical and mechanical connectors which fit to corresponding connectors provided on the examination arm. The connectors (not shown) provide electrical supply for driving the means 6. Additionally, the connectors ensure means 6 is held in position with respect to the means for image receiving. In the case of an analog apparatus, means 6 includes a slot 10 for inserting a cassette containing radiation sensitive film to be printed. Such a slot is not ordinarily provided in a digital apparatus.
When taking image at different degrees of magnification, means for magnification, such as a plate 12, is used. The magnification plate can be fixed onto examination arm 4 at two possible positions and comprises a material transparent to the radiation, at least in its part in the radiation path. The patient""s breast rests on the upper platform of the magnification plate. Depending on the position of the plate, the breast is closer to or further from the radiation source and further from or nearer to the cassette containing the radiation sensitive film or the means for image receiving. Because of beam divergence, the various magnification positions consequently correspond to different degrees of magnification of the image of the breast. To change from one magnification factor to another, it is necessary to dismount or disconnect or remove or displace the magnification plate and dispose it at another position on the examination arm. Magnification factors are also limited by the number of positions for the magnification plate on the examination arm.
This known apparatus has the disadvantages of requiring several independent devices. Additionally, changing the magnification ratio involves dismounting and remounting the magnification plate. This complicates the operator""s task and prolongs the duration of each examination. Magnification factors are also limited by the number of positions for the magnification plate on the examination arm.
An embodiment of the invention is a radiograph apparatus that allows images to be taken with varying magnification factors in simple manner without requiring demounting and remounting operations to be performed on the apparatus.
In one embodiment of the invention, a radiographic apparatus has a source for delivering radiation towards a means for receiving an image, and means for supporting an object to be imaged, such as a breast, mounted adjacent to the means for receiving an image. The means for support comprises a body and plate that can be moved with respect to the body of the means for support. The plate is moved in the direction of propagation of the radiation and consequently allows the image enlargement to be varied.
In another embodiment of the invention, means for support of an object to be imaged, such as a breast, for a radiographic apparatus, has a body and a plate that can be moved with respect to the body. The plate is transparent to the radiation employed in the apparatus and can be moved with respect to the body in a direction substantially perpendicular to its surface.